1/* Low-level locking access to futex facilities. Linux version.
2 Copyright (C) 2005-2018 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library. If not, see
17 <http://www.gnu.org/licenses/>. */
18
19#ifndef _LOWLEVELLOCK_FUTEX_H
20#define _LOWLEVELLOCK_FUTEX_H 1
21
22#ifndef __ASSEMBLER__
23#include <sysdep.h>
24#include <tls.h>
25#include <kernel-features.h>
26#endif
27
28#define FUTEX_WAIT 0
29#define FUTEX_WAKE 1
30#define FUTEX_REQUEUE 3
31#define FUTEX_CMP_REQUEUE 4
32#define FUTEX_WAKE_OP 5
33#define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE ((4 << 24) | 1)
34#define FUTEX_LOCK_PI 6
35#define FUTEX_UNLOCK_PI 7
36#define FUTEX_TRYLOCK_PI 8
37#define FUTEX_WAIT_BITSET 9
38#define FUTEX_WAKE_BITSET 10
39#define FUTEX_WAIT_REQUEUE_PI 11
40#define FUTEX_CMP_REQUEUE_PI 12
41#define FUTEX_PRIVATE_FLAG 128
42#define FUTEX_CLOCK_REALTIME 256
43
44#define FUTEX_BITSET_MATCH_ANY 0xffffffff
45
46/* Values for 'private' parameter of locking macros. Yes, the
47 definition seems to be backwards. But it is not. The bit will be
48 reversed before passing to the system call. */
49#define LLL_PRIVATE 0
50#define LLL_SHARED FUTEX_PRIVATE_FLAG
51
52#ifndef __ASSEMBLER__
53
54#if IS_IN (libc) || IS_IN (rtld)
55/* In libc.so or ld.so all futexes are private. */
56# ifdef __ASSUME_PRIVATE_FUTEX
57# define __lll_private_flag(fl, private) \
58 ({ \
59 /* Prevent warnings in callers of this macro. */ \
60 int __lll_private_flag_priv __attribute__ ((unused)); \
61 __lll_private_flag_priv = (private); \
62 ((fl) | FUTEX_PRIVATE_FLAG); \
63 })
64# else
65# define __lll_private_flag(fl, private) \
66 ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
67# endif
68#else
69# ifdef __ASSUME_PRIVATE_FUTEX
70# define __lll_private_flag(fl, private) \
71 (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
72# else
73# define __lll_private_flag(fl, private) \
74 (__builtin_constant_p (private) \
75 ? ((private) == 0 \
76 ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex)) \
77 : (fl)) \
78 : ((fl) | (((private) ^ FUTEX_PRIVATE_FLAG) \
79 & THREAD_GETMEM (THREAD_SELF, header.private_futex))))
80# endif
81#endif
82
83#define lll_futex_syscall(nargs, futexp, op, ...) \
84 ({ \
85 INTERNAL_SYSCALL_DECL (__err); \
86 long int __ret = INTERNAL_SYSCALL (futex, __err, nargs, futexp, op, \
87 __VA_ARGS__); \
88 (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (__ret, __err)) \
89 ? -INTERNAL_SYSCALL_ERRNO (__ret, __err) : 0); \
90 })
91
92#define lll_futex_wait(futexp, val, private) \
93 lll_futex_timed_wait (futexp, val, NULL, private)
94
95#define lll_futex_timed_wait(futexp, val, timeout, private) \
96 lll_futex_syscall (4, futexp, \
97 __lll_private_flag (FUTEX_WAIT, private), \
98 val, timeout)
99
100#define lll_futex_timed_wait_bitset(futexp, val, timeout, clockbit, private) \
101 lll_futex_syscall (6, futexp, \
102 __lll_private_flag (FUTEX_WAIT_BITSET | (clockbit), \
103 private), \
104 val, timeout, NULL /* Unused. */, \
105 FUTEX_BITSET_MATCH_ANY)
106
107#define lll_futex_wake(futexp, nr, private) \
108 lll_futex_syscall (4, futexp, \
109 __lll_private_flag (FUTEX_WAKE, private), nr, 0)
110
111/* Returns non-zero if error happened, zero if success. */
112#define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
113 lll_futex_syscall (6, futexp, \
114 __lll_private_flag (FUTEX_CMP_REQUEUE, private), \
115 nr_wake, nr_move, mutex, val)
116
117/* Returns non-zero if error happened, zero if success. */
118#define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
119 lll_futex_syscall (6, futexp, \
120 __lll_private_flag (FUTEX_WAKE_OP, private), \
121 nr_wake, nr_wake2, futexp2, \
122 FUTEX_OP_CLEAR_WAKE_IF_GT_ONE)
123
124/* Priority Inheritance support. */
125#define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \
126 lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)
127
128#define lll_futex_timed_wait_requeue_pi(futexp, val, timeout, clockbit, \
129 mutex, private) \
130 lll_futex_syscall (5, futexp, \
131 __lll_private_flag (FUTEX_WAIT_REQUEUE_PI \
132 | (clockbit), private), \
133 val, timeout, mutex)
134
135
136#define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex, \
137 val, private) \
138 lll_futex_syscall (6, futexp, \
139 __lll_private_flag (FUTEX_CMP_REQUEUE_PI, \
140 private), \
141 nr_wake, nr_move, mutex, val)
142
143#endif /* !__ASSEMBLER__ */
144
145#endif /* lowlevellock-futex.h */
146